import math
class Point:
    def __init__(self):
        self.pointA=[]
        self.pointB=[]
    def setValue(self,x1,y1,x2,y2):
        self.pointA=[x1,y1]
        self.pointB=[x2,y2]
class Line(Point):
    def getLen(self):
        self.len=math.sqrt(math.fabs((self.pointA[0]-self.pointB[0])*2+(self.pointA[1]-self.pointB[1])*2))
        return self.len

lin = Line()
lin.setValue(3,4,5,6)
print(lin.getLen())